Bicycle Chain Ring Ramps for Faster Shifting Under Load
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Solution Overview
Problem
Conventional bicycle chain rings struggle with quick shifting, especially during extreme loading conditions like sprinting or out-of-saddle climbing, as existing solutions either increase stress on the chain or do not effectively address up-shifting performance.
Innovation Solution
The design incorporates a bicycle chain ring with strategically placed ramps and features such as inside tapers, beveled teeth, and partially cutoff teeth to facilitate efficient up-shifting by engaging multiple chain links and reducing stress on the chain, utilizing ramps with lifting surfaces and angled knife edges to enhance shifting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional chain rings are used with lateral pushing motion, then shifting is adequate for most purposes, but shifting is slow under extreme loading conditions
Solution Approach 1:
Instead of pushing the chain laterally from the side (conventional approach), the invention uses ramps that lift the chain upward from below during up-shifts and pull it downward during down-shifts. This inverted vertical motion mechanism overcomes the slowness of lateral pushing under extreme loading conditions.
Solution Approach 2:
The invention changes the motion parameter from lateral horizontal movement to vertical lifting/pulling movement. The ramps create a vertical component of chain motion that is more effective under high load, transforming the shifting mechanism's fundamental motion characteristic.
2Device complexity
If conventional chain rings push the chain laterally, then the mechanism is simple, but stress on the chain increases leading to wear
Solution Approach 1:
The ramps change the direction and nature of the force applied to the chain from lateral pushing to vertical lifting/pulling. This parameter change in force application reduces the harmful stress components on the chain while maintaining derailleur mechanism simplicity.
3Speed
If lateral pushing is used for down-shifting, then the mechanism is simple, but the chain cannot disengage quickly from the larger chain ring
Solution Approach 1:
The invention adds localized features (ramps and notches) to specific areas of the chain ring without redesigning the entire structure. The ramps are positioned at the inner surface to assist chain disengagement, while the outer teeth structure remains conventional, maintaining simplicity where not needed.
Solution Approach 2:
For down-shifting, the ramps work in reverse to pull the chain downward onto the smaller chain ring, and the notches provide escape paths that facilitate quick disengagement from the larger ring, inverting the conventional approach of relying solely on lateral pushing.
Data Source
AI summary
A bicycle chain ring, including an inner edge fully circumscribing both an opening and an axis of rotation; an inner surface extending between the inner edge and an outer edge where a plurality of chain ring teeth emanate; and a plurality of ramps disposed about the inner surface, wherein at least one of the plurality of ramps has a lifting surface configured to concurrently engage at least one link of a bicycle chain at two or more distinct pivot points along the length of the chain link to initiate stable lift of the bicycle chain without assistance from any of the plurality of chain ring teeth; wherein the lifting surface has a first end proximate the inner edge and a second end proximate the outer edge.